Interrupter-bushing

ABSTRACT

An electrical interrupter-bushing is depicted which provides a unitary cast envelope having end sealing members integrally cast with the envelope. The envelope is adapted to accommodate separable electrodes in hermetically sealed relationship within the bore of the glass-ceramic envelope. The lower portion of the envelope is adapted to extend within a cabinet and will accommodate a current transformer. Thus, a single unitary structure is provided which operates as an entrance bushing and as an interrupter envelope.

ilnited States Patent [191 Larkin INTERRUPTER-BUSHING [75] Inventor: Oscar L. Larkin, Jackson, Miss.

[73] Ass'ignee: Allis-Chalmers Corporation,

Milwaukee, Wis.

[22] Filed: Dec. 3, 1973 [21] Appl. No.: 421,394

[52] US. Cl 200/144 B [51] Int. Cl. HOIH 33/66 [58] Field of Search 200/144 B [56] References Cited UNITED STATES PATENTS 3,590,184 6/1971 Wachta et a1. ZOO/144 B 3,626,123 12/1971 Pflanz et al. ZOO/144 B FOREIGN PATENTS OR APPLICATIONS 1,030,798 5/1966 United Kingdom ZOO/144 B Aug. 5, 1975 Primary ExaminerRobert S. Macon Attorney, Agent, or FirmRobert C. Jones [57] ABSTRACT An electrical interrupter-bushing is depicted which provides a unitary cast envelope having end sealing members integrally cast with the envelope. The envelope is adapted to accommodate separable electrodes in hermetically sealed relationship within the bore of the glass-ceramic envelope. The lower portion of the envelope is adapted to extend within a cabinet and will accommodate a current transformer. Thus, a single unitary structure is provided which operates as an entrance bushing and as an interrupter envelope.

2 Claims, 2 Drawing Figures 1 N E B PTER-, U HIN BACKGROUND or 'jrniziNvEuTIoN "envelope is locatedwithin'the bushingnand the entire assemblage is then placed in an operative position in the enclosure. The"anrarigement -is both.,massive and costly and not particularly well adapted to meet environmental requirements of present standards. With separate devices, the connection and alignment are difficult, both in the initial arrangeme ntand thereafter in maintainingthe ope rative relatiofnship.I

s i M RYoF THE INVENTION In accordanceiwith th vention, there is provided a combined unitary interrupter-lbushingfiievice which is particularly suitable for use lfeither 'oilor" gas insulation installations. i I

9 Accordingly "t is 'a g'eiieral object of'tlie invention to provide an. im roved circuitiritertiiptef liiishing structure of the type 'reducigsithe'fim of the entire interrupter-bushing striicture,;th:iis' reducing the space requirements. R n

Another o bj ec't of the 'ih ve ri onl'is; to provide a'unitary interrupter-bji'isl'lirigparticularly suitable for mold casting. 5

Still another object of the invention is to provide a unitary glass-ceia'micfjenvelopesuitable for combined interrupter-bushing usage. 7

Yet anothe'r objelc t of the'inventicin isto provide a unitary cast 'glass c er'amic envelope for an'int'errupterbushing jdevice, inee'ts' eleetricali requirements and is of reduced'sizeu 1 DESCRIPTlQNfQI- TH E DRAWINGS FIG. 1 is'a'view'jriar ifiiilevtidri andf-partly in vertical sectionjshowing'j'the ir-i ternalarrangement of the interrupt ei fbiisliing :the iinveiitiori; and,

FIG. 2" isja -vi'ew iritrarisverse section through the interrupter-bushing take "n a'plarfe"represented by the line II II irriril'ci. '1. f

pp 'eiit ionisdepictedasavacuum interrupter-bush' g l'fl wliichiis pafticirlarly well adapted for operation at groundpdte'n'tialfoiuse with a dead tank arrangement. The interrupter-bushingqo includes an elongated fhoi'lldvif c"lindric"al' ifi eiiiber 12 that is proternal a l ly sp which ar xial boi'e-"M' and'a plurality of upper ex-..

ses 19 to accommodate fastening devices such as bolts 21.

As depicted in FIG. 2, the flange 17 is formed with four identical lobes 26, 27, 28 and 29 each being spaced equidistantly apart with respect to adjacent lobes. Each lobe is formed with smoothly contoured corners, such as the corners 26A and 26B of the lobe 26. The corners 26A and 26B are located equidistantly apart from a radial line which passes through the axial center X and extends through a point 26C on the peripheral surface of the lobe 26. With this arrangement the corners26A and 26B of the lobe 26 will be below an arc whose center is located at a point 28C and which is tangent to the point 26C. The description, as applied to the lobe 26, is equally applicable to the lobes 27, 28 and 29 and all the lobes are identical in construction and arrangement. The configuration of the envelope 12 permits the casting of the insulating envelope in a simple split mold which may be hinged for production and convenience. In this respect a mold hinged at location point 28C, or at any other point on a line extending radially outward from point 28C, will permit a split hinged mold to open readily in a swinging motion without locking either by'interference or seizure of the cast envelope. The described profiling of the envelope flange 17, wherein every point on the flange perimeter is to swing away from the casting itself, permits the use of an automated process in casting the envelope, such as by multiposition indexing machines capable of centrifugal casting while indexing between dwell periods.

The hollow cylindrical member 12 extends below the flange 17 to provide an extension 31. The upper external portion 12, the lower portion 31 and the flange 17 are cast integrally in a single mold to provide an integral unit construction without seams. As shown, the lower portion 31 of the interrupter-bushing is provided with external corrugations 32 which provide an increased creep distance greater than a ratio of 1.

The upper axial end 33 is provided with a ring 34 that is integrally cast in vacuum tight relationship in the axial end face 36 of the end 33 of the member 12. The ring 34 is provided with an outwardly extending radial flange portion 37 which serves as a base for receiving a cap 38 likewise having a radial outwardly extending flange portion 39 which is complementary to the flange 37 of the ring 34. The cap 38 is welded or otherwise secured in vacuum tight relationship to the ring 34. The

'undersurface of the end cap 38 is provided with reinforcing ribs 42 which operate to give added support to a fixed electrode 43. The fixed electrode 43 extends downwardly through an axially aligned opening provided in the end cap 38 and extends downwardly into the bore 14 of the member 12 to a position adjacent to a movable electrode 46. Evacuation of the interior of the memberl2 is effected through a pinch-off tube 47 in the usual manner. The fixed electrode or contact stud 43 is provided with a disc type arc shield 48, which is preferably of high purity copper, that is brazed or 6O 'welded to the stud 43.

the axis of the bore 14 of the member 12. The disc 51 is integrally cast into the wall of the bore 14 adjacent to the-bottom of the portion 31 in vacuum tight relationship. The disc 51 is provided with an annular axially 1 extending collar portion 52 which serves as a mounting base for an elongated tubular arc shield 56. The are shield 56 is secured, as by being welded, into the opening of the disc collar 52 in vacuum sealed relationship as shown. The interfit of the lower end of the shield 56 in the collar portion 52 of the disc 51 operates to provide mechanical strength to the bond or weld that is effected between the disc 51 and lower end 57 of the shield 56. The lower end of the arc shield 56 is counterbored as at 58 to provide a shoulder 59 against which a supporting disc 61 abuts and is brazed thereto. The disc 61 is provided with an axial opening through which the axially movable contact stud 66 extends.

The axially movable contact stud 66 is provided with an abutment or washer 67 to which one end of a cylindrical bellows 68 is brazed or welded. The other end of bellows 68 is brazed or welded to the disc 61 to provide a vacuum seal between the movable contact stud 66 and the interior of the portion 31.

It should be noted that the glass-ceramic insulating member 12, the cooperating ring 34 and disc 51 provide a physically rugged, weather resistant envelope which is capable of operating as a vacuum interrupterbushing envelope as herein disclosed. It should also be noted that the provision of the ring 34 and the disc 51, which are integrally cast in vacuum tight relationship in the member 12, require no other bonding material or metalizing components to provide a structurally strong and vacuum tight seal between the ring and the member 12 or the disc 51 and the member 12. This construction facilitates the manufacturing process in that the member 12 is centrifugally cast with the ring 34 and disc 51 being cast therein in the same operation. Heretofore, as is well known, it has been necessary to form the member 12 of a material such as alumina ceramic which is provided with a metalized coating deposit for fusion to a metallic surface or with a silica base additive to the metalized coating deposit.

Electrostatic shielding means have been normally employed at opposite ends ofa bushing envelope to reduce or eliminate voltage gradients which would otherwise occur and provide corona discharge in high voltage outdoor use of a device, such as the device 10. Heretofore. rings, such as the ring 34, the disc 51 and the end 33 of the member 12 are provided with an electrically conductive coating which is applied by brush, spray or dipping and one which would firmly adhere to the ceramic. This coating would be of a molybdenummanganese alloy fired at a temperature sufficient to cause fusion sintering of the coating and the silica in the ceramic type envelope. This coating would then be provided with a nickel plate by an electrochemical or electroless chemical bath so that a ring, such as ring 34, could be brazed to this bonding material. Other methods of adhering a member, such as a member 34, to a ceramic envelope have been accomplished by using a bonding adhesive to secure a ring to a ceramic envelope in vacuum tight relationship. It is therefore apparent that the construction of the envelope as herein disclosed in which the ring 34 and the ring or disc 51 is integrally cast in vacuum tight relationship with the member 12 in one operation eliminates the necessity of providing sealing means between a metallic member such as the ring 34 and disc 51 and the glass-ceramic insulating member 12.

As shown in FIG. 1, the lower end 31 of the interrupter-bushing is particularly well adapted to accommodate a current transformer 71. A bus 72 is electrically connected to the axially movable electrode 46 by operation of a flexible connector 73. The stationary electrode 43 receives a bus 74. Axial movement of the movable electrode 46 is effected by a lift rod operator 76 that has a pivotal connection as at 77 with an insulated push-rod 78. The push-rod 78 is, in turn, operatively connected to the lower end of the electrode 46.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In an interrupter-bushing;

a housing of a glass-ceramic insulating material constructed and arranged in the form of an elongated cylindrical envelope having an axial bore;

an external annular flange having four identical lobes spaced equidistantly apart integrally formed with said elongated cylindrical envelope, said flange being located substantially midway between the axial ends of said envelope thereby dividing said envelope into an upper portion and a lower portion;

plurality of external annular sheds integrally formed with said elongated cylindrical envelope on the portion thereof above said flange;

plurality of external annular sheds integrally formed with said elongated cylindrical envelope on the portion thereof below said flange, said sheds operating to increase the creep distance with a ratio greater than one;

a metallic circular member hermetically fused in one axial end of said envelope, said metallic circular member having a radially extending annular flange;

a metallic disc hermetically fused in the wall of the bore of said envelope at the opposite axial end thereof, said metallic disc having an axial opening which coincides with the axis of said envelope, said metallic disc also having an axially extending collar;

a metallic sealing plate secured to said flange of said circular envelope in hermetically sealed relationship, said sealing plate having an axial bore;

a stationary electrode extending into the bore of said envelope through the opening in said sealing plate in hermetically sealed relationship within the opening in said sealing plate;

a tubular shield extending into the bore of said envelope through the axial opening in said disc, said tubular shield being hermetically sealed to said collar of said disc, said shield being of a length to extend upwards a distance sufficient to encompass the depending end of said stationary electrode;

a movable electrode extending into the bore of said envelope through said tubular shield, said movable electrode being of a length to engage with the adjacent axial end of said stationary electrode when in closed position;

a bellows encompassing said movable electrode within the bore of said envelope adjacent the end of the bore through which said movable electrode enters said envelope, oneend of said bellows being hermetically sealed to said tubular shield and hav ing its opposite end connected in hermetically sealed relationship to said movable electrode,

a disc shield secured to said stationary electrode and disposed in spaced relationship to the adjacent axial end of said tubular shield;

6 a first disc secured in hermetically sealed relationship said second disc encompassing the lower end of to the lower end of said movable electrode, said said movable contact and being secured in hermetifirst disc having the inner end of said bellows secally sealed relationship to said tubular shield. cured in hermetically sealed relationship thereto; 2. An interrupter-bushing according to claim 1 and, 5 wherein said bore of said envelope is filled with a dia second disc having an axial opening of a diameter electric gaseous insulating medium.

larger than the diameter of said movable electrode, 

1. In an interrupter-bushing; a housing of a glass-ceramic insulating material constructed and arranged in the form of an elongated cylindrical envelope having an axial bore; an external annular flange having four identical lobes spaced equidistantly apart integrally formed with said elongated cylindrical envelope, Said flange being located substantially midway between the axial ends of said envelope thereby dividing said envelope into an upper portion and a lower portion; a plurality of external annular sheds integrally formed with said elongated cylindrical envelope on the portion thereof above said flange; a plurality of external annular sheds integrally formed with said elongated cylindrical envelope on the portion thereof below said flange, said sheds operating to increase the creep distance with a ratio greater than one; a metallic circular member hermetically fused in one axial end of said envelope, said metallic circular member having a radially extending annular flange; a metallic disc hermetically fused in the wall of the bore of said envelope at the opposite axial end thereof, said metallic disc having an axial opening which coincides with the axis of said envelope, said metallic disc also having an axially extending collar; a metallic sealing plate secured to said flange of said circular envelope in hermetically sealed relationship, said sealing plate having an axial bore; a stationary electrode extending into the bore of said envelope through the opening in said sealing plate in hermetically sealed relationship within the opening in said sealing plate; a tubular shield extending into the bore of said envelope through the axial opening in said disc, said tubular shield being hermetically sealed to said collar of said disc, said shield being of a length to extend upwards a distance sufficient to encompass the depending end of said stationary electrode; a movable electrode extending into the bore of said envelope through said tubular shield, said movable electrode being of a length to engage with the adjacent axial end of said stationary electrode when in closed position; a bellows encompassing said movable electrode within the bore of said envelope adjacent the end of the bore through which said movable electrode enters said envelope, one end of said bellows being hermetically sealed to said tubular shield and having its opposite end connected in hermetically sealed relationship to said movable electrode, a disc shield secured to said stationary electrode and disposed in spaced relationship to the adjacent axial end of said tubular shield; a first disc secured in hermetically sealed relationship to the lower end of said movable electrode, said first disc having the inner end of said bellows secured in hermetically sealed relationship thereto; and, a second disc having an axial opening of a diameter larger than the diameter of said movable electrode, said second disc encompassing the lower end of said movable contact and being secured in hermetically sealed relationship to said tubular shield.
 2. An interrupter-bushing according to claim 1 wherein said bore of said envelope is filled with a dielectric gaseous insulating medium. 